Reverse circulation hammer with modular bit

ABSTRACT

Embodiments provide apparatuses and methods for excavation and drilling, particularly reverse circulation hammers and bits. Reverse circulation hammers and bits manufactured in accordance with various embodiments may help to prevent fatigue and breaking of the bit during a drilling operation, may prevent clogging of return holes, may provide higher efficiency drilling operations, and may provide modular bit designs that may be interchanged to suit a particular drilling operation.

TECHNICAL FIELD

Embodiments herein relate to the field of excavation, and, more specifically, to apparatus and methods for drilling, particularly reverse circulation drilling.

BACKGROUND

Reverse circulation (RC) drilling is a type of excavation that uses a pneumatic reciprocating piston known as a hammer to drive a tungsten-steel drill bit. Reverse circulation is achieved by blowing air down the drilling rods or shafts, the differential pressure creating air-lift of the water and cuttings up one or more inner tubes that are inside each rod or shaft.

The most commonly used RC drill bits are 5-8 inches in diameter and have round metal ‘buttons’ that protrude from the bit, which are used to drill through shale and abrasive rock. As the buttons wear down, drilling becomes slower and the rod string can potentially become bogged in the hole. This is a problem, as trying to recover the rods may take hour, days, or even weeks. The rods and drill bits themselves are very expensive, often resulting in great cost to drilling companies when equipment is lost down the bore hole. Additionally, when something is lost (e.g., breaks off) in the hole, it is usually not the drill string, but rather from the bit, hammer, or stabilizer to the bottom of the drill string (bit). This breakage is often caused by a blunt bit getting stuck in fresh rock, over-stressed metal, or a fresh drill bit getting stuck in a part of the hole that is too small, owing to having used a bit that has worn to smaller than the desired hole diameter.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments will be readily understood by the following detailed description in conjunction with the accompanying drawings. Embodiments are illustrated by way of example and not by way of limitation in the figures of the accompanying drawings.

FIG. 1 illustrates an elevation view of an example of a hammer assembly, in accordance with various embodiments;

FIG. 2 illustrates an exploded view of an example of a hammer, in accordance with various embodiments;

FIG. 3 illustrates a cross sectional view of an example of a hammer, in accordance with various embodiments;

FIGS. 4A and 4B illustrate an elevation view (FIG. 4A) and a cross sectional view (FIG. 4B) of an example of a top drive sub, in accordance with various embodiments;

FIGS. 5A and 5B illustrate an elevation view (FIG. 5A) and a cross sectional view (FIG. 5B) of an example of a control tube, in accordance with various embodiments;

FIGS. 6A and 6B illustrate an elevation view (FIG. 6A) and a cross sectional view (FIG. 6B) of an example of a back head, in accordance with various embodiments;

FIGS. 7A and 7B illustrate an elevation view (FIG. 7A) and a cross sectional view (FIG. 7B) of an example of a piston, in accordance with various embodiments;

FIGS. 8A and 8B illustrate an elevation view (FIG. 8A) and a cross sectional view (FIG. 8B) of an example of an outer shroud, in accordance with various embodiments;

FIG. 9 illustrates an example of an inner porting barrel, in accordance with various embodiments;

FIG. 10 illustrates a cross sectional view of an example of a porting barrel, in accordance with various embodiments;

FIG. 11 illustrates an elevation view of an example of a porting barrel assembly with a check valve in a closed position, in accordance with various embodiments;

FIG. 12 illustrates an elevation view of an example of a porting barrel assembly with a check valve in an open position, in accordance with various embodiments;

FIGS. 13A and 13B illustrate top (FIG. 13A) and bottom (FIG. 13B) views of an example of a porting barrel, in accordance with various embodiments;

FIGS. 14A and 14B illustrate ISO views of an example of a radial exhaust check valve (FIG. 14A) and a spring (FIG. 14B), in accordance with various embodiments;

FIGS. 15A and 15B illustrate an ISO view (FIG. 15A) and a cross sectional view (FIG. 15B) of an example of a porting barrel shroud ring, in accordance with various embodiments;

FIGS. 16A and 16B illustrate an elevation view (FIG. 16A) and an ISO view (FIG. 16B) of an example of a bit keeper plate, in accordance with various embodiments;

FIGS. 17A and 17B illustrate an elevation view (FIG. 17A) and an ISO view (FIG. 17B) of an example of a bit drive plate with wear protection, in accordance with various embodiments;

FIGS. 18A and 18B illustrate an elevation view (FIG. 18A) and an ISO view (FIG. 18B) of an example of a bit guide bushing, in accordance with various embodiments;

FIG. 19 illustrates an exploded view of an example of a modular bit, in accordance with various embodiments;

FIGS. 20A and 20B illustrate a cross sectional view (FIG. 20A) and an ISO view (FIG. 20B) of an example of a modular bit center shaft, in accordance with various embodiments;

FIGS. 21A, 21B and 21C illustrate a top view (FIG. 21A), an ISO view (FIG. 21B), and a bottom view (FIG. 21C) of an example of a modular bit face plate, in accordance with various embodiments;

FIGS. 22A, 22B and 22C illustrate a top view (FIG. 22A), a bottom view (FIG. 22B), and a cross sectional view (FIG. 22C) of an example of a modular bit outer drive ring, in accordance with various embodiments;

FIGS. 23A and 23B illustrate a top view (FIG. 23A) and an elevation view (FIG. 23B) of an example of a modular bit retainer, in accordance with various embodiments;

FIG. 24A and 24B illustrate an elevation view (FIG. 24A) and a cross sectional view (FIG. 24B) of an example of a modular bit assembly, in accordance with various embodiments;

FIG. 25 illustrates an ISO view of an example of a modular bit assembly, in accordance with various embodiments;

FIG. 26 illustrates an exploded view of an example of a modular ring bit system, in accordance with various embodiments;

FIG. 27 illustrates a perspective view of an example of a drive adapter, in accordance with various embodiments;

FIG. 28 illustrates an exploded view of an example of an assembled porting barrel, adapter, adapter keys, and larger bit, in accordance with various embodiments;

FIGS. 29A and 29B illustrate a top view (FIG. 29A) and a perspective view (FIG. 29B) of an exampled of an adapter key, in accordance with various embodiments;

FIG. 30 illustrates an elevation view of an example of an assembled porting barrel, adapter, and larger bit, in accordance with various embodiments;

FIGS. 31A and 31B illustrate an elevation view (FIG. 31A) and a cross sectional view (FIG. 31B) of a key drive system, in accordance with various embodiments;

FIG. 32 illustrates an exploded view of the same key drive system illustrated in FIGS. 31A and 31B, in accordance with various embodiments;

FIG. 33 shows an elevational exploded view of an alternate top drive sub, referred to herein as a radial shock sub, in accordance with various embodiments;

FIGS. 34A-34C illustrate elevation (FIG. 34A), top (FIG. 34B), and cross-sectional (FIG. 34C) views of a radial shock sub, in accordance with various embodiments;

FIG. 35 illustrates a perspective exploded view of a radial shock sub, in accordance with various embodiments;

FIG. 36 illustrates a cross-sectional view of another embodiment of a reverse circulation hammer in which the bit is in a closed position; in accordance with various embodiments;

FIGS. 37A and 37B illustrate close-up views of the reverse circulation hammer of FIG. 36, in accordance with various embodiments; and

FIG. 38 illustrates the reverse circulation hammer of FIG. 36 in full bit drop position, in accordance with various embodiments.

DETAILED DESCRIPTION OF DISCLOSED EMBODIMENTS

In the following detailed description, reference is made to the accompanying drawings which form a part hereof, and in which are shown by way of illustration embodiments that may be practiced. It is to be understood that other embodiments may be utilized and structural or logical changes may be made without departing from the scope. Therefore, the following detailed description is not to be taken in a limiting sense, and the scope of embodiments is defined by the appended claims and their equivalents.

Various operations may be described as multiple discrete operations in turn, in a manner that may be helpful in understanding embodiments; however, the order of description should not be construed to imply that these operations are order dependent.

The description may use perspective-based descriptions such as up/down, back/front, and top/bottom. Such descriptions are merely used to facilitate the discussion and are not intended to restrict the application of disclosed embodiments.

The terms “coupled” and “connected,” along with their derivatives, may be used. It should be understood that these terms are not intended as synonyms for each other. Rather, in particular embodiments, “connected” may be used to indicate that two or more elements are in direct physical or electrical contact with each other. “Coupled” may mean that two or more elements are in direct physical or electrical contact. However, “coupled” may also mean that two or more elements are not in direct contact with each other, but yet still cooperate or interact with each other.

For the purposes of the description, a phrase in the form “A/B” or in the form “A and/or B” means (A), (B), or (A and B). For the purposes of the description, a phrase in the form “at least one of A, B, and C” means (A), (B), (C), (A and B), (A and C), (B and C), or (A, B and C). For the purposes of the description, a phrase in the form “(A)B” means (B) or (AB) that is, A is an optional element.

The description may use the terms “embodiment” or “embodiments,” which may each refer to one or more of the same or different embodiments. Furthermore, the terms “comprising,” “including,” “having,” and the like, as used with respect to embodiments, are synonymous.

Disclosed herein is an RC hammer and modular bit that, in embodiments, may separate the torque input area from the hammer impact area, resulting in an RC hammer and bit that is less prone to breakage than a conventional RC hammer and bit. When rotational torque is applied to an area that is already under impact stress (e.g., from the hammer), it may create an area where failure is likely to happen, for instance, fatigue or fracture. Thus, a conventional bit shank is susceptible to failure near the keys or splines that deliver rotational torque to the bit. Shock waves travel down the bit shank from the hammer impact area and dissipate as they travel. Thus, increasing the distance between the hammer impact area and the torque input area may result in an RC hammer and bit that is less prone to breakage. In various embodiments, the RC hammers and bits disclosed herein may have a generally smooth shank, with no keys or splines in the impact area.

In addition, in various embodiments, an external drive mechanism may be used to transfer torque to the bit instead of a conventional internal drive mechanism. Because rotational drive features (for instance, a hex drive system, a key drive system, external splines, or any other type of external drive mechanism that transfers torque) may be located the outside of the shaft, this may allow them to be positioned farther from the hammer, increasing the integrity of the shaft, and further reducing the likelihood of failure. Additionally, in embodiments, an external drive system may be more effective than a conventional internal drive system. Because it generally is more efficient to transfer torque on the outside of the bit, a shorter coupling area may be used, which may reduce the bit weight. By contrast, the smaller diameter of the conventional internal drives requires a longer and deeper engagement area to effectively transfer torque. Thus, in embodiments, the shorter coupling area of the disclosed bits may reduce the weight of the bit.

Also disclosed in various embodiments is a bit face having a modular design. In embodiments, the bit face may include vertical return holes for returning air, water, and debris up the shaft and out of the system. Some embodiments may include a three-part bit face with three return holes, however any number of return holes may be used, and a modular bit face as disclosed herein may have 4, 5, 6, or even more return holes. In various embodiments, the straight vertical return holes may be advantageous because eliminating bends in the return path may prevent the return holes from becoming clogged with debris during use. In some embodiments, the return holes may be tapered or have a draft angle, which further facilitates the passage of debris through the front face and into the return channels. In particular embodiments, the return channels may widen (e.g., form a funnel shape) as they pass through the bit face, allowing debris to pass freely. For instance, in a particular example, the opening at the front side of the face plate may be approximately 2 inches across, while the opening at the back side of the face plate may be larger, for instance approximately 2.5 or 3 inches across. In even more particular examples, the return holes in the shank also may be tapered so there is little or no restriction when debris enters the center bit. In some embodiments, when a larger diameter face plate is used, a greater number of return holes are included.

In various embodiments, the modular bit may include a shank or striker, a drive ring, and a face plate. In some embodiments, all three of the main parts of the modular bit may be swapped out for other shanks, face plates, or drive rings. For instance, in some embodiments, a drive ring with a key drive system may be swapped for one with a hex drive system. Similarly, face plate with three return holes may be swapped for one with a different configuration, for instance, one with five or six holes. Additionally, in embodiments, the face plate may be swapped to suit the particular application. For instance, a face plate with an aggressive button, such as a parabolic button or a ballistic button, may be used for excavating soft formations or substrates, and then a face plate with a normal rock button, such as a dome button, may be substituted when a harder or very hard substrate is encountered. Also, in various embodiments, the face plate may be easily replaced when the buttons are worn. In some embodiments, any worn parts of the modular bit system may be replaced if fatigued.

In additional embodiments, the outer drive ring may be removed and replaced with a modular component adapter such as for an overburden ring, a ring bit system, or an underreamer, or with a larger or smaller diameter bit in order to vary the hole size. This adapter may have a ring drive on one end for coupling with the shaft and another end adapted to couple to, for instance, an overburden or underreamer bit. An overburden bit may be used, for example, for advancing casing (for instance, a pile or steel tube) through unconsolidated formations that may collapse or undermine during drilling.

Still other embodiments include an RC and modular bit with an improved check valve system. A conventional hammer has valves that are different sizes on the front and back sides. For instance, a conventional hammer might have a check valve that is one square inch on the back side, and smaller on the front side. This may produce back pressure during drilling, for instance where water heads exceed about 50 meters or 150 feet. For instance, particularly when excavating underwater, the pressure of the water, combined with the back pressure, might total 250 lbs. In embodiments, the RC hammers of the present disclosure may include a single check valve that may result in a more open exhaust flow through the hammer. Because the single check valve uses an annular system instead of a single or multiple stem valves, it permits greater air flow through the hammer. In some embodiments, this may create less back pressure, because it generally is desirable to have a high operating pressure and a low back pressure for increased efficiency. In one specific, non-limiting example, the ratio of the area of the valve on the front and back side may be 1:1, so under 200 feet of water, it might only require, for example, 100 lbs of pressure to open the check valve instead of, for instance, 130 or 140 pounds to open it with a conventional check valve. In other words, a high back pressure may undesirably offset the operating pressure.

In further embodiments, the hammer may be decoupled from the bit without disassembling the hammer, for instance by collapsing the spring retainer and removing the outer ring and face plate. In a conventional hammer, it is necessary to strip the hammer down in order to remove the bit. In some embodiments, in the disclosed system, because bit-retaining plates may be used to retain the bit, the hammer never has to be disassembled. In specific examples, the bit may be removed by actuating the internal cylinder, which may cause it to drip the bit.

FIG. 1 illustrates an elevation view of an example of a hammer assembly 10, FIG. 2 illustrates an exploded view of the same example of hammer assembly 10, and FIG. 3 illustrates a cross sectional view of the same example of hammer assembly 10, in accordance with various embodiments. FIGS. 1, 2, and 3 illustrate the connectivity of a number of components, all of which are discussed in detail below.

FIGS. 4A and 4B illustrate an elevation view (FIG. 4A) and a cross sectional view (FIG. 4B) of an example of a top drive sub 20, in accordance with various embodiments. Referring to FIG. 4B, top drive sub 20 may include a first radial groove air chamber 22 and an air hole 24 connecting first radial groove air chamber 22 to the bottom of top drive sub 20. Also included in some embodiments is a first bolt hole 26 that may connect top drive sub 20 to the back head 40 (see, e.g., FIG. 6, which is discussed below).

FIGS. 5A and 5B illustrate an elevation view (FIG. 5A) and a cross sectional view (FIG. 5B) of an example of a control tube 30, in accordance with various embodiments. In this example, control tube 30 may include a first radial diameter 32 which may fit into the third internal bore 46 of back head 40 (see, e.g., FIG. 6, which is discussed below), and a first hole or slot 34, which may be common to the first radial groove 45 of back head 40 (see, e.g., FIG. 6). In this example, control tube 30 also may include a second hole or slot 36, which may be common to the second radial groove air chamber 54 of the piston 50 (see, e.g., FIGS. 7A and 7B, which are discussed below). Also included in various embodiments is an annulus 37, which may connect first hole or slot 34 to a second hole or slot 36. In this example, control tube 30 also may include a first internal bore 38 for debris return.

FIGS. 6A and 6B illustrate an elevation view (FIG. 6A) and a cross sectional view (FIG. 6B) of an example of back head 40, in accordance with various embodiments. In the illustrated embodiment, back head 40 may include a first threaded hole 41 that may connect top drive sub 20 to back head 40. Also included in various embodiments is a third hole or slot 42 that may connect a third internal bore for air chamber 44 to first radial groove 45. Also included in some embodiments is a second bolt hole 43 that may connect back head 40 to an inner porting barrel 70 via a second threaded hole 87. In various embodiments, first radial groove 45 may connect first threaded hole 41 to third hole or slot 42. Also included in various embodiments is a third internal bore 46, that may seal fit to first radial diameter 32, a first notch 47 that may connect back head 40 to an outer shroud 60, a first external diameter 48 that may seal fit to a first internal seal diameter 64 of outer shroud 60. Also included in some embodiments is an internal bore 49 to fit a fourth external diameter 74 of a porting barrel 70 (see, e.g., FIG. 9, which is discussed below).

FIGS. 7A and 7B illustrate an elevation view (FIG. 7A) and a cross sectional view (FIG. 7B) of an example of a piston 50, in accordance with various embodiments. This embodiment may include a second external diameter 52 that may fit to a second radial groove 88 in porting barrel 70 (see, e.g., FIG. 9, which is discussed below). Embodiments also may include a second radial groove air chamber 54 that may be common to second hole or slot 36 of control tube 30, a sixth internal bore 56 that may supply air from control tube 30 to a seventh internal bore 89 of inner porting barrel 70 (see, e.g., FIG. 9, which is discussed below), and an impact face 58 of piston 50.

FIGS. 8A and 8B illustrate an elevation view (FIG. 8A) and a cross sectional view (FIG. 8B) of an example of outer shroud 60, in accordance with various embodiments. In some embodiments, outer shroud 60 may include a third external diameter 61, a second notch 62 in outer shroud 60, first internal seal diameter 64 that may fit to first external diameter 48 of back head 40, a second internal seal diameter 65 that may fit to the external seal 92 of a radial exhaust check valve 90 (see, e.g., FIGS. 14A and 14B, which are discussed below). Also included in some embodiments are an internal diameter clearance 66 for a seventh external diameter 91 of radial exhaust check valve 90 (see, e.g., FIGS. 14A and 14B), and a third internal seal diameter 68 that may fit to an eighth external diameter 104 of a porting barrel shroud ring 100 (see, e.g., FIGS. 15A and 15B, which are discussed below).

FIG. 9 illustrates an elevation view of an example of porting barrel 70, in accordance with various embodiments, and FIG. 10 illustrates a cross sectional view of an example of porting barrel 70, in accordance with various embodiments. Turning now to FIG. 10, porting barrel 70 may include a first face surface 71, a fourth hole or slot 73 common to second radial groove 88 and an annulus of the outer shroud 60 and porting barrel 70, a fourth external diameter 74, an external under cut diameter 75, and an exhaust pocket 76 connecting the fourth external diameter 74 to a fifth external diameter 81. Some embodiments also may include a second radial diameter 77, which may fit to an eighth internal bore 106 of the porting barrel shroud ring 100 (see, e.g., FIGS. 15A and 15B, which are discussed below), a fifth hole 78, a first slot 80, which may fit to a first side surface 114 of a bit keeper plate 110 (see, e.g., FIGS. 16A and 16B, which are discussed below) and second slot 136 of bit guide bushing 130 (see, e.g., FIGS. 18A and 18B, which are discussed below). Also included in some embodiments is a fifth external diameter 81, a pocket 82 with a floor and perpendicular sides for a drive plate 120 (see, e.g., FIGS. 17A and 17B, which are discussed below), an exhaust air slot 84, a sixth external diameter 86 that may fit to a thirteenth internal bore 182 of a modular bit outer drive ring 170 (see, e.g., FIGS. 22A, 22B and 22C, which are discussed below), a second threaded hole 87 that may connect the back head 40 to the porting barrel 70, second radial groove 88 that may connect to fourth hole or slot 73, and a seventh internal bore 89 that may fit to the second external diameter 52 of piston 50 and the ninth external diameter 132 of the bit guide bushing 130 (see, e.g., FIGS. 18A and 18B, which are discussed below).

FIG. 11 illustrates an elevation view of an example of a porting barrel assembly with a check valve in the closed position, FIG. 12 illustrates an elevation view of an example of a porting barrel assembly with a check valve in the open position, and FIGS. 13A and 13B illustrate top (FIG. 13A) and bottom (FIG. 13B) views of an example of a porting barrel, in accordance with various embodiments.

FIGS. 14A and 14B illustrate ISO views of an example of a radial exhaust check valve 90 (FIG. 14A) and a spring 98 (FIG. 14B), in accordance with various embodiments. In various embodiments, radial exhaust check valve 90 may include a seventh external diameter 91, an external seal 92, an internal diameter 94 that may fit to spring 98, a fourth internal seal 96, and spring 98.

FIGS. 15A and 15B illustrate an ISO view (FIG. 15A) and a cross sectional view (FIG. 15B) of an example of porting barrel shroud ring 100, in accordance with various embodiments. In various embodiments, porting barrel shroud ring 100 may include a radial seal groove 102, an eighth external diameter 108 that may fit to third internal seal diameter 68 of outer shroud 60, and an eighth internal bore 106 that may fit to second radial diameter 77 of porting barrel 70.

FIGS. 16A and 16B illustrate an elevation view (FIG. 16A) and an ISO view (FIG. 16B) of an example of a bit keeper plate 110, in accordance with various embodiments. In various embodiments, bit keeper plate 110 may include a third radial diameter 112 that may fit to third internal seal diameter 68 of outer shroud 60, a first side surface 114 with an adjacent radius that may fit to first slot 80 of porting barrel 70, and a radial internal diameter 116 with an adjacent radius and angle sides that may fit to a third radial groove 142 of a modular bit center shaft 140 (see, e.g., FIGS. 20A and 20B, which are discussed below).

FIGS. 17A and 17B illustrate an elevation view (FIG. 17A) and an ISO view (FIG. 17B) of an example of a bit drive plate 120 with wear protection, in accordance with various embodiments. Some embodiments of bit drive plate 120 may include a second side surface 122 with an adjacent radius that may fit to pocket 82 of porting barrel 70, a third threaded hole 124, a wear plate 126 such as a Delrin wear plate, a third side surface 128 with perpendicular walls that may fit to wear plate 126, and a bottom surface 129 that may fit to the floor of pocket 82 of porting barrel 70.

FIGS. 18A and 18B illustrate an elevation view (FIG. 18A) and an ISO view (FIG. 18B) of an example of a bit guide bushing 130, in accordance with various embodiments. Some embodiments of bit guide bushing 130 may include a ninth external diameter 132 that may fit to seventh internal bore 89 of porting barrel 70, a sixth hole 134, a second slot 136 that may be common to the first slot of porting barrel 70 and that may fit to first side surface 114 of bit keeper plate 110, and a ninth internal bore 138 that may fit to tenth external diameter 141 of modular bit center shaft 140.

FIG. 19 illustrates an exploded view of an example of a modular bit, and FIGS. 20A and 20B illustrate a cross sectional view (FIG. 20A) and an ISO view (FIG. 20B) of an example of modular bit center shaft 140, in accordance with various embodiments. In various embodiments, modular bit center shaft 140 may include a tenth external diameter 141 that may fit to the ninth internal bore 138 of bit guide bushing 130, a third radial groove 142 with adjacent angled sides that may fit to radial internal diameter 116 of bit keeper plate 110, a tenth internal bore 143 that may fit to first internal bore 38 of control tube 30, an internal bore debris return 144, a fourth radial groove 145 with adjacent sides that may fit to a fifth radial groove 180 of a modular bit outer drive ring 170 and modular bit retainer 150. In some embodiments, modular bit retainer 150 may be replaced with another retainer mechanism, such as retention plates or a key drive system. Some embodiments of modular bit center shaft 140 also may include an exhaust slot 146 that may be common to an exhaust air hole 173 hole of modular bit outer drive ring 170, a surface of a hex 147 that may fit to an internal hex surface 178 of modular bit outer drive ring 170, an internal taper 148 bore of a debris return opening 163 (such as a diamond shaped debris return opening) of a modular bit face plate 160, and an internal counter bore 149 that may fit to a second external radial diameter 166 of modular bit face plate 160.

FIGS. 21A, 21B and 21C illustrate a top view (FIG. 21A), an ISO view (FIG. 21B), and a bottom view (FIG. 21C) of an example of modular bit face plate 160, in accordance with various embodiments. In various embodiments, modular bit face plate 160 may include a surface of a hex 161 that may fit to an internal hex surface 178 of modular bit outer drive ring 170 and that may be aligned with the surface of hex 147 of modular bit center shaft 140. Additionally, some embodiments may include a first face slot 162 that may be aligned with a second face slot 174 of modular bit outer drive ring 170 and that may intercept debris return opening 163 that may be common to internal taper bore 148 of modular bit center shaft 140. Also included in some embodiments is a second external radial diameter 164 that may fit to an eleventh internal bore 179 of modular bit outer drive ring 170, a first carbide compact 165, and a surface contact 167 with a wall adjacent internal counter bore 149 of modular bit center shaft 140.

In some embodiments, a diamond-shaped debris return opening 163 of modular bit face plate 160 may be particularly useful when drilling through unconsolidated formations with varying silts, sands, cobbles, and/or gravels of varying sizes. In various embodiments, the diamond shape may prevent round pieces of rock from blocking off the return because air will still be able to flow through the corners of the diamonds, preventing plugging or blocking. In various embodiments, other shapes may be more advantageous for drilling through solid rock. For instance, in some embodiments, a round hole may be effective because the cutting size may be more uniform, for instance in the case of 1 inch to ¼ inch cuttings. Additionally, in some embodiments, when a larger size face plate is used, more return holes may be desirable because they may maximize return airflow and increase drilling efficiency.

FIGS. 22A, 22B and 22C illustrate a top view (FIG. 22A), a bottom view (FIG. 22B), and a cross sectional view (FIG. 22C) of an example of modular bit outer drive ring 170, in accordance with various embodiments. In various embodiments, modular bit outer drive ring 170 may include an eleventh external diameter 171, a second face surface 172, an exhaust air hole 173 that may connect exhaust slot 146 of modular bit center shaft 140 and exhaust air slot 84 of porting barrel 70, and a second face slot 174 aligned with the exhaust air hole 173 that may connect first face slot 162 to debris return opening 163 of modular bit face plate 160. Embodiments also may include a second carbide compact 175, an internal slot with adjacent sides that may be aligned with bit drive plate 120 to pocket 82 of porting barrel 70, a radius slot 177, an internal hex surface 178 aligned with the second surface of hex 161 of modular bit face plate 160 and first surface of the hex 147 of modular bit center shaft 140, an eleventh internal bore 179, a fifth radial groove 180 with adjacent sides that may fit to first external radial diameter 152 of modular bit retainer 150. Further embodiments also may include a third face surface 181 generally perpendicular to a twelfth internal bore 182 and contacting the adjacent face of sixth external diameter 86 of porting barrel 70, the twelfth internal bore 182, which may fit to the sixth external diameter 86 of the porting barrel 70, a thirteenth internal bore 183, which may fit to the radial diameter adjacent to exhaust slot 146, and a twelfth external diameter 184, which may fit to third internal seal diameter 68 of outer shroud 60.

FIGS. 23A and 23B illustrate a top view (FIG. 23A) and an elevation view (FIG. 23B) of an example of a modular bit retainer 150, in accordance with various embodiments. In some embodiments, modular bit retainer 150 may include a first external radial diameter 152 with adjacent faces that may fit to the fifth radial groove 180 of modular bit outer drive ring 170, and an internal radial diameter 154 that may fit to fourth radial groove 145 of modular bit center shaft 140. Although not illustrated, in some embodiments, bit retainer 150 may be replaced with other bit retention systems, such as retention plates (similar to the bit shank retention plates) or a key drive system.

FIG. 24A and 24B illustrate an elevation view (FIG. 24A) and a cross sectional view (FIG. 24B) of an example of a modular bit assembly and a cross sectional view of an example of an assembly, FIG. 25 illustrates an ISO view of an example of a modular bit assembly, and FIG. 26 illustrates an exploded view of an example of a modular ring bit system, all in accordance with various embodiments.

Returning to FIG. 2, in various examples, rotational torque may be supplied by hydraulic, electric, or any other means to impart rotation via the drill pipe or connections to top drive sub 20, which may be connected to back head 40, which in turn may be coupled to internal porting barrel 70. In various embodiments, it then may project into external pocket 82, which may then be connected to drive plate 120, which may fit into internal radius slot 177 of modular bit outer drive ring 170, and then torque may be transferred to internal hex surface 178 and the surface of hex 161 of modular bit face plate 160, and the first surface of hex 147 of modular bit center shaft 140.

In various embodiments, modular outer drive ring 170 may allow the use of a shorter bit length than conventional drive systems. In embodiments, this may result in a much lighter bit, which may increase the impact force of the hammer. For instance, an example of a conventional bit may weigh about 360-380 pounds, but the modular bit disclosed herein may have a mass of about 250 pounds, for instance. In various embodiments, a lighter bit may be advantageous because impact energy from the pneumatic piston will act on the lighter weight to transfer more of the impact energy.

In some embodiments, the external drive may allow a drive adapter to be used to accommodate larger diameter bits. FIG. 27 illustrates a perspective view of an example of a drive adapter 200, FIG. 28 illustrates an exploded view of an example of an assembled porting barrel 70, drive adapter 200, adapter keys 202, and larger bit 204, FIGS. 29A and 29B illustrate a top view (FIG. 29A) and a perspective view (FIG. 29B) of an example of adapter key 202, and FIG. 30 illustrates an elevation view of an example of an assembled porting barrel 70, adapter 200, and larger bit 204, in accordance with various embodiments. As illustrated in FIG. 27, in some embodiments, adapter ring 200 may be equipped with adapter key holes 206, and as shown in FIG. 28, may be configured to couple to porting barrel 70 and larger bit 204 via adapter keys 202 that fit within adapter key holes 206 and corresponding key holes 208 on porting barrel 70. In some embodiments, coupling adapter 200 and larger bit 204 to porting barrel 207 with adapter keys 202 may allow larger bit 204 and adapter 200 to have a shorter profile, since a large area of engagement between the components is not required. This, both adaptor 200 and larger bit 204 may have a smaller mass (and hence the device may have greater efficiency) than comparably-sized bits and drive systems.

In various embodiments, the modular bit assembly may be retained by bit keeper plate 110 through retainer slot 80 of the inner porting barrel fitting through second slot 136 of bit guide bushing 130, into third radial groove 142 of modular bit center shaft 140. In various embodiments, the keeper plate may be held in place by third radial diameter 112, which may fit into the third internal seal diameter 68 of the outer shroud 60.

An alternative embodiment of the rotational drive system is illustrated in FIGS. 31 and 32. FIGS. 31A and 31B illustrate an elevation view (FIG. 31A) and a cross sectional view (FIG. 31B) of a key drive system, and FIG. 32 illustrates an exploded view of the same key drive system illustrated in FIGS. 31A and 31B, in accordance with various embodiments. In various embodiments, back head 340 may transfer torque to outer shroud 360 via drive back head drive keys 342 that may fit into back head key pockets 344 and corresponding outer shroud key slots 361. In various embodiments, this key drive system may withstand more rotational torque than other drive systems and may result in less wear and tear on drive components.

In embodiments, the bit and outer ring assembly may be guided in two areas. In various embodiments, the shank may be guided by the internal bushing, and the ring may be guided by the external radial diameter of the barrel. In various embodiments, this may provide a more stable alignment during use, and may help prevent wobble in the system, which may cause the bit to cock off and drill an inaccurate hole, in addition to causing excess wear and tear. Additionally, in some larger embodiments, a guide bushing may be added in this area that overlies the keys. Such a guide bushing may allow a replaceable piece to wear, rather than the keys. One example of such a bushing is a bronze manganese bushing.

In various embodiments, air may be supplied via a dual wall drill pipe connected to the top drive sub via first radial groove 22 through air hole 24 into second internal bore 44 of back head 40. In various embodiments, this may then travel through first hole or slot 34, into annulus 37, and out of second hole or slot 36 of control tube 30, and into second radial groove air chamber 54 of piston 50. In embodiments, this may start the cycle of the piston imparting impact energy into the striking face adjacent to tenth external diameter 141 of modular bit center shaft 140, into modular bit face plate 160, and into modular outer drive ring 170, producing a pneumatic percussive impact

In various embodiments, different retainers may be used for different bit weights. In specific examples, the retainer may be a spring ring, one or more segments, or ball bearings. In one specific example, for a 150 lb bit, a spring retainer may be used, but with a heavier bit, for instance over 350 lbs, a segment retainer may be selected instead.

In embodiments, during the cycling of piston 50, exhaust air may be expelled through fourth hole or slot 73 into the annulus between outer shroud 60 and fourth external diameter 74 of inner porting barrel 70. In various embodiments, the exhaust path may be sealed by first interior seal diameter 64 of outer shroud 60, and by first external diameter 48 of back head 40. Additionally, in some embodiments, the exhaust path pay be further sealed by external seal 92 and fourth internal seal 96 of radial exhaust check valve 90, which may connect with mating surface 65 of outer shroud 60, and fourth external diameter 74 of inner porting barrel 70. In embodiments, this seal also may be held closed by spring 98, which may be located in internal diameter 94 radial exhaust check valve 90, and against face of porting barrel shroud ring 100.

In particular examples, after the exhaust pressure reaches a nominal 6 pounds (or other predetermined level), radial exhaust check valve 90 may open. In various embodiments, in this position, exhaust air may flow through exhaust pocket 76 of inner porting barrel 70, under porting barrel shroud ring 100, into the annulus between fifth external diameter 81 of inner porting barrel 70, and third internal seal diameter 68 of outer shroud 60, into exhaust air slot 84 of inner porting barrel 70, to exhaust air hole 173, and into second face slot 174 of modular bit outer drive ring 170 to first face slot 162, into debris return opening 163 of modular bit face plate 160, removing cuttings and debris from the bit during drilling. In various embodiments, the air then may pass into internal taper bore 148, internal bore debris return 144, and first internal bore for debris return 38, to the center return of the drill pipe, thus completing debris evacuation.

An alternate embodiment of top drive sub 20 is shown in FIGS. 33-35. FIG. 33 shows an elevational exploded view of radial shock sub 420, FIGS. 34A-34C illustrate elevation (FIG. 34A), top (FIG. 34B), and cross-sectional (FIG. 34C) views of radial shock sub 420, and FIG. 35 illustrates a perspective exploded view of radial shock sub 420, in accordance with various embodiments. This alternate drive sub, radial shock sub 420, may include bolts 422 that may secure top adapter plate 424 to barrel 426 and/or housing 428. As shown in FIGS. 33-35, spindle 430 may couple to housing 428 via a plurality of spindle keys 432 that may fit within spindle key receiving pockets 434 and housing key slots 436. In various embodiments, first 438 and second 440 polymer rings may provide impact-absorbance between housing 428 and spindle 430 (e.g., first polymer ring) and/or between barrel 426 and spindle 430. In various embodiments radial shock sub 420 (also referred to as a cylinder alignment shock sub) may replace the hex drive of top drive sub 20 with a key drive mechanism. In some embodiments, radial shock sub wear plates 442, such as Delrin wear plates, may be provided.

Generally speaking, a hex drive system must be somewhat loose in order to function. In various embodiments, substitution with a key drive system may shorten the area of contact required between the drive components, allowing radial shock sub 420 to be a shorter component that top drive sub 20. Additionally, in some embodiments, the closer fit of the key drive system may keep the components in closer alignment and prevent them from deflecting relative to one another. In various embodiments, first and second polymer rings 438, 440 may serve to absorb recoil and reduce vibration and wear and tear on the system.

FIGS. 36, 37A, 37B, and 38 illustrate another embodiment of a reverse circulation hammer in which air is routed through the device in such a way and at such a time as to maximize strike efficiency. FIG. 36 illustrates an example of a reverse circulation hammer 500 with a bit in a closed position, which may occur at the beginning of a piston strike cycle, in accordance with various embodiments. This position is also illustrated in a close-up view in FIG. 37A, in accordance with various embodiments. As shown in FIG. 37A, in the start position, feed air slots 577 may be open slightly. For instance, in some embodiments, feed air slots may be open one half inch or less, for instance, about 0.2, 0.3, or 0.4 inches. Additionally, in various embodiments, in the start position, the piston port 575 a may not be aligned with the fourth hole or slot 573 a in the inner porting barrel 570. In contrast, in various embodiments, as illustrated in FIG. 37B, when the bit is in a strike position and has advanced forward, for instance less than half an inch, such as about 0.2, 0.3, or 0.4 inches, feed air slots 577 may be closed and piston port 575 a may align at least partially with fourth hole or slot 573 a to create an air conduit through which air may exhaust.

FIG. 38 illustrates an example of a full bit drop position, in which the piston and bit have dropped further, for instance about 2.3 inches or less, for instance about 2 inches or about 1.7 inches. In various embodiments, this position may allow feed air slots 577 to assume a fully open position, and for upper and lower piston ports 575 a and 575 b to more fully align with upper and lower fourth holes or slots 573 a and 573 b, which may allow air to exhaust from the lift chamber. In various embodiments, this venting system may allow the bottom chamber (e.g., below the piston) to exhaust air during a piston strike, which may prevent the formation of an air cushion and that may increase the strike efficiency of a piston stroke.

Although certain embodiments have been illustrated and described herein, it will be appreciated by those of ordinary skill in the art that a wide variety of alternate and/or equivalent embodiments or implementations calculated to achieve the same purposes may be substituted for the embodiments shown and described without departing from the scope. Those with skill in the art will readily appreciate that embodiments may be implemented in a very wide variety of ways. This application is intended to cover any adaptations or variations of the embodiments discussed herein. Therefore, it is manifestly intended that embodiments be limited only by the claims and the equivalents thereof. 

1. A reverse circulation hammer and drill bit comprising: a drive sub configured to receive rotational torque; a back head coupled to the drive sub and configured to receive rotational torque therefrom; a porting barrel coupled to the back head and configured to receive rotational torque therefrom; a modular bit coupled to the porting barrel and configured to receive rotational torque therefrom; and a pneumatic reciprocating piston configured to transmit impact force to the modular bit via a modular bit shaft at a hammer impact area; wherein the hammer strike zone is does not receive rotational torque directly form the drive sub, back head, or porting barrel.
 2. The reverse circulation hammer and drill bit of claim 1, wherein the porting barrel comprises a generally cylindrical shape having a wall and an inner bore, and wherein the pneumatic reciprocating piston is adapted to fit within the inner bore of the porting barrel.
 3. The reverse circulation hammer and drill bit of claim 2, wherein rotational torque is transmitted via the wall and impact force is transmitted within the inner bore via the pneumatic reciprocating piston.
 4. The reverse circulation hammer and drill bit of claim 1, wherein the hammer impact area is free of keys, splines, and hex drive features.
 5. The reverse circulation hammer and drill bit of claim 1, wherein the piston is free of keys, splines, and hex drive features.
 6. The reverse circulation hammer and drill bit of claim 1, wherein the drive sub, back head, and porting barrel comprise an external rotational drive mechanism.
 7. The reverse circulation hammer and drill bit of claim 6, wherein the external rotation drive mechanism comprises one or more key drive, hex drive, or external spline systems.
 8. The reverse circulation hammer and drill bit of claim 6, wherein the external rotational drive system comprises a cylinder having an external surface, and internal surface, and an inner bore, and wherein the one or more key drive, hex drive, or external spline systems is located on the outer surface of the cylinder.
 9. The reverse circulation hammer and drill bit of claim 1, wherein the modular bit and the porting barrel are coupled at a coupling area, and wherein the coupling area is less than about five inches tall.
 10. The reverse circulation hammer and drill bit of claim 1, wherein the drill bit has a mass of about 250 pounds or less.
 11. The reverse circulation hammer and drill bit of claim 1, further comprising an annular check valve.
 12. A modular drill bit for use with a reverse circulation hammer, wherein the drill bit comprises an outer drive ring and a bit face plate, and wherein the drill bit further comprises a plurality of vertical return holes configured to allow the passage of air, water, and/or debris through the bit face and up through the reverse circulation hammer.
 13. The modular drill bit of claim 12, wherein the vertical return holes comprise substantially no bends.
 14. The modular drill bit of claim 12, wherein the bit face plate comprises a front face and back surface, and wherein the vertical return holes have a smaller diameter at the front face of the bit face plate than on the back face of the bit face plate.
 15. The modular drill bit of claim 12, wherein the drill bit comprises from about 3 to about 6 vertical return holes.
 16. The modular drill bit of claim 12, wherein the vertical return holes have a draft angle configured to facilitate the passage of debris.
 17. The modular drill bit of claim 12, wherein the outer drive ring is configured to receive rotational torque.
 18. The modular drill bit of claim 12, wherein the modular drill bit further comprises a shank and a striker.
 19. The modular drill bit of claim 18, wherein the outer drive ring, bit face plate, shank, and striker are replaceable.
 20. The modular drill bit of claim 12, wherein the outer drive ring comprises a key drive system, a hex drive system, or a spline drive system.
 21. The modular drill bit system of claim 12, wherein the outer drive ring is configured to be removed and replaced with a modular component adapter.
 22. The modular drill bit system of claim 21, wherein the modular component adapter comprises an overburden ring, a ring bit system, an underreamer, or an adapter for a larger or smaller bit. 